Gwen Channels ELLE for L'Oreal

Gwen Stefani`s in Cannes for a few reasons—sun, food, family fun—but the pop icon's first order of business was shooting her third and latest commercial for L'Oreal. Yesterday, she spent twelve hours filming on a yacht, in a villa, and against an eternity pool (she swears she only got tired around hour 10).

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The campaign won't debut until September (when No Doubt's new album hits shelves), but she did offer one great hint after lunch this afternoon when I mentioned ELLE's May cover.

Though no one does a red lip quite like Gwen, the nude she wore on the cover was a big hit in our office—as well as L'Oreal's. She said, "That's what L'Oreal was really inspired by! We wanted that look for the commercial so we did a version of that—with the hair. I loved that hair; I was always very much into Bewitched and a Samantha look."

As for tonight's look, when she heads to Hotel du Cap for the annual AmFar gala, she'll be wearing a dress of her own design. "I haven't made very many couture gowns—it's a big process and a lot of work and it's a lot of pressure because there are so many beautiful gowns out there that I could wear, but I really wanted to make something with L.A.M.B. because I really wanted to auction it off," Stefani said.